Tell me some ways to get resources.

Just the combat unit has its limits. You need to upgrade resource production buildings and capture tiles simultaneously. Don't forget to keep an eye on daily quests and events, hmm!

Even when fighting the same battle group, the rewards differ based on my combat power. Could it be that your combat power is too low, or are you fighting a battle group that doesn't match your combat power?

Even at S2 level, you can quickly gather resources just by doing battle squad and bunker tasks, so there are no restrictions on needed tasks...